A Preliminary Evaluation of Factors Influencing the Distribution and Abundance of Macrophytes in the Mackenzie Delta Lakes

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A Preliminary Evaluation of Factors Influencing the Distribution and Abundance of Macrophytes in the Mackenzie Delta Lakes

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Title: A Preliminary Evaluation of Factors Influencing the Distribution and Abundance of Macrophytes in the Mackenzie Delta Lakes
Author: Squires, MM; Huebert, D; Lesack, LFW
Abstract: The Mackenzie Delta of the Canadian arctic is a complex environment containing 25,000 lakes, where flooding of the lakes may exert considerable control over the ecological characteristics of the lakes in the system. For instance, lakes which are flooded regularly are turbid and lakes which are flooded infrequently are relatively clear. The availability of light may profoundly influence the pattern of primary production among the Delta lakes and in particular the productivity of macrophytes. 'Corresponding to the light gradient, there are physical and chemical gradients which may interact with light to ultimately determine the distribution and abundance of macrophytes among the lakes. Macrophyte biomass and various edaphic factors were measured along a light gradient in a subset of Delta lakes. Macrophyte biomass increased sharply where average light attenuation was lower than 1.4 m-1. Increases in macrophyte biomass correspond to increases in porewater phosphate but do not correspond to pore-water ammonia. The role of light in controlling macrophytic growth is not surprising, however, the possible role of sedimentary phosphorus is unusual with respect to lakes in general where nitrogen limitation of submersed macophytes may be more common. However, our data cannot discern whether pore-water phosphate is a cause or an effect of increased macrophyte biomass. It is also possible that a positive-feedback mechanism is at work where macrophytes initially enhance the availability of phosphorus associated with sediments which then leads to increased macrophyte production.
Description: American Academy of Underwater Sciences (http://www.aaus.org/)
URI: http://archive.rubicon-foundation.org/9736
Date: 1998

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